voltage drop problem in the head light ***FIXED***

Hi all, been a while since I've been here.
Mad rush to get the Norton registered for the ride downt to Phillip Island (Oct) for the MotoGP.

New 12 volt battery installed (been tested since installation) and I get 11.7 volts at the battery and about 10.8 to 11.0 at the head light bucket but when I switch on the head light the volts drop to at least 8.
My father who is a sparkie has checked all the wiring and we can't seem to find any faulty earth or kinked wire.

It all seems to happen as soon as the H4 head light bulb 65/55w is plugged in because the wiring going to the head light lamp seems ok. New H4 bulb 65/55w but same thing.
I'm at work at the moment so I can't sight the bike or do anything. Tonight I was going to kick the bike over and then switch on the head lights and see if they still come on but I imagine they won't get near enough the right volts to be bright enough.

I'm thinking it's the black plastic plug the bulb plugs into, has anyone else ever had a problem like this?

Re: voltage drop problem in the head light

brasstinman
You could try relays for your headlight hi/low beam. http://easternbeaver.com/
It might be in your switchgear at the handlebars.
I've dealt with this guy and he sells a quality product for most M/C
"11.7 volts at the battery".... That’s kinda low for a new battery. :shock: should be above 12.5 volts before things are switched on.
CNN

Re: voltage drop problem in the head light

Canuck is right.

First, get a battery that provides 12.5 v fully charged.

Second, install 2 relays near the headlight, under the tank or in the shell, if there's room. One for the brights, one for the dim.

Third, run a minium 12 gauge line from the battery directly to the normally-open contact of each relay. This will allow for a max of 0.1-0.2 volts of drop to the headlight filaments. Connect each wiper to each filament.

Enjoy the clear night-time riding that comes with a full-wattage headlamp.

Re: voltage drop problem in the head light

If ole 'Sparkle' says wires and switches check out to flow ok then I'd suspect the battery has a bad cell or 3 and can't handle the draw. Decent low battery should read 12.5 v, full good battery 13.2. I'm just repeating alerts above.
There are half size 30 amp relays. I was able to fit 3 in head lamp shell and it did indeed add to the bright whiteness and no more heat from bar switches resistance.
A fun if a bit tricky circuits to relay but even w/o decent battery and alternator should be fine light beam if rev'd over 1800 rpm.

Re: voltage drop problem in the head light

You've gotten good advice above, which I would paraphrase/summarize as follows:

- You have TWO problems. Your battery is shot (or perhaps your charging system, but let's hope it's just the battery!); and

- You have a wiring problem BETWEEN your battery and the headlamp.

- I'd test your charging system, but assuming it's not that, you need a new battery. (If it IS the charging system, god knows it may have damaged the battery by now so you may need a new battery also....).

- The easiest and BEST solution to your voltage drop is to replace the (I assume) stock wiring with a relayed connection. I'm another big fan of EasternBeaver.com. Check it out.

- Get a good H4 bulb (and lens, if you haven't already) . Raybrig the best IMHO, but SPENDY!!!! Philips "Vision Plus" pretty good but get the Euro ones - meaning buy from a Euro/UK vendor, not US. Plenty of other good ones out there I'm sure, but these are my faves (RAYBRIG!! - but don't blame me when you see the price.)

Best of luck.

Re: voltage drop problem in the head light

Thanks heaps for all your replies and the more I read the more it sounds like the switches are possibly causing a voltage drop to the head light. I've had a chat to my father and we're going to get some 12 volt relays and get these wired up to the head light but can't do this until Sat.
Great site by the way http://easternbeaver.com/ Thanks for passing that along.

In the mean time I'm going to call the battery place and let them know I'm bringing the battery in tomorrow and get that sorted out because I'm not a happy chappy about the 11.7 volts after a full charge.

I'll keep you all posted.

Once again thank you all so much for your quick assistance.

Re: voltage drop problem in the head light

Good news! Two new wires from the battery to 2x relays with 2x 15 amps and a spare battery from my father and the bike kicked over perfectly. It was so good to hear it rumbling.

Now to get the kill switch wired up and I'm ready for the rego test.

Does anyone know where to connect the kill switch up on an electronic ignition?

Re: voltage drop problem in the head light

brasstinman said:

Does anyone know where to connect the kill switch up on an electronic ignition?

Click to expand...

Positive or negative earth/ground?

And which 'electronic' ignition?

Power goes from battery to key to kill button then on to electronic ign. Key off or kill tap cuts power. This of course can be run to switch a relay that feeds the real power to Ing. so only switching current ever flows through the key and kill button path. Elect. Ing. never draw up to 5 amps current for sizing components.
Just 'cause I had a 5 amp 12 v audio power supply filter on hand I put that inline to Boyer to steady its brains from the voltage jerks of my tiny battery the alternator pumped through. A big battery of course steadies the pluses as does a blue cap can.